Switching from ultra-fast-growing to slower-growing broiler breeds is considered the single most impactful welfare improvement possible in the poultry industry.
Fast-growing broiler breeds represent one of the most extreme cases of welfare compromised by genetic selection. Their bodies grow so rapidly that their cardiovascular and skeletal systems cannot keep pace, causing chronic pain, immobility, and heart failure. Slower-growing breeds that reach slaughter weight in 56-70 days have dramatically lower rates of these problems, are more active, and display more normal behaviour. The trade-off is higher production cost and longer growing period, both of which are reflected in higher consumer prices. The welfare benefit per bird is very large.